The first periodic law stated by Mendeleev was:a)There is no correlati...
The first periodic law stated by Mendeleev was, "the physical and chemical properties of the elements are a periodic function of their atomic weights (atomic masses)." The elements having similar properties appeared in the same group (vertical column).
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The first periodic law stated by Mendeleev was:a)There is no correlati...
Explanation:
Mendeleev's periodic law is the foundation of the modern periodic table. It states that the properties of elements are a periodic function of their atomic weights. This means that when elements are arranged in order of increasing atomic weights, their properties repeat in a periodic manner.
Details:
Mendeleev was a Russian chemist who developed the first version of the periodic table in 1869. He arranged the elements in order of increasing atomic weights and noticed that elements with similar properties appeared at regular intervals. This led him to propose the periodic law.
Properties of Elements:
The properties Mendeleev was referring to include physical and chemical properties such as atomic radius, ionization energy, electronegativity, and chemical reactivity. He observed that elements with similar properties were grouped together in columns called groups or families.
Periodic Function:
The term "periodic function" means that there is a repeating pattern or cycle. In the case of Mendeleev's periodic law, the properties of elements repeat periodically as you move across the periodic table. This periodicity is due to the repeating pattern of electron configurations as you move from one element to the next.
Atomic Weights:
Mendeleev arranged the elements in order of increasing atomic weights because atomic weights were the known properties at the time. However, it was later discovered that atomic weights were not always accurate due to the existence of isotopes. Isotopes are atoms of the same element with different numbers of neutrons, resulting in different atomic masses.
Modern Periodic Table:
The modern periodic table is based on the atomic number, which represents the number of protons in an atom's nucleus. The atomic number provides a more accurate representation of an element's identity and its position in the periodic table. The elements are still arranged in order of increasing atomic numbers, and their properties still exhibit periodicity.
Conclusion:
In conclusion, the first periodic law stated by Mendeleev is that the properties of elements are a periodic function of their atomic weights. This law laid the foundation for the development of the modern periodic table, which is based on the atomic number rather than atomic weight. The periodicity of properties is due to the repeating pattern of electron configurations as you move across the table.
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